Recently our car decided to start missing. It got worse over a couple of days and finally quit. We replaced the plugs, plug wires, coil, and coil harness. The car was (still is) running great, and the check engine light had gone out. But then it came back on after driving a few miles down the road. We disconnected the battery to reset it, but then it just comes back on after you drive a little while. There is nothing wrong with the car as far as we can tell now. Any idea why the light would stay on?

You should be able to go to a local autozone and they'll pull the codes off for free. Once you have the code, you can search this forum for it - you'll prolly find someone has already had that problem and you'll know what to replace.

I don't know about where you guys live, but here in cali autozones don't pull codes for free anymore. I dunno why, something about the shops not getting business or some crap. Hopefully where you live they can do it.

Why dont you follow the procedure below, it will show you how to enter 'test' mode on your car, and to get the DTC code (error code) and scroll further down to read it's description.

Here is a bit of info for the test mode of the focus dash .. long but informative

To access the test mode, hold the trip meter reset button in and turn the key to the on position, then the guages will do a full sweep and state guage on the LCD.. you are then able to prett the button to get the details

Chris

/--------------------------------------------------------\

First digit structure is as follows:

Pxxxx for powertrain
Bxxxx for body
Cxxxx for chassis
Uxxxx for future systems

Second digit structure is:

P0xxx Government required codes
P1xxx Manufacturer codes for additional emission system function; not required but reported to the government

Third digit structure is:

Px1xx measurement of air and fuel
Px2xx measurement of air and fuel
Px3xx ignition system
Px4xx additional emission control
Px5xx speed and idle regulation
Px6xx computer and output signals
Px7xx transmission
Px8xx transmission
Px9xx control modules, input and output signals

The fourth and fifth digits designate the individual components and systems.

Here's a generic list of DTC codes for reference, makes the post a bit long but should do. These are for SAE standard ones, as used for SAE J2012 OBD-II:

Anatomy of the Diagnostic Trouble Code

A DTC is made up of 5 digits. The figure below demonstrates the
composition of a DTC. With this information it is easier to trouble shoot a DTC
without knowing the description of the code.
X X X X X

B-Body
C-Chassis
P-Powertrain
U-Network

0-SAE
1-MFG

1-Fuel and Air Metering
2-Fuel and Air Metering (Injector circuit)
3-Ignition Systems or Misfire
4-Auxiliary Emission Controls
5-Vehicle Speed Control and Idle Control System
6-Computer Output Circuit
7-Transmission System
8-Transmission

Fault 00-99

Types of DTC's
There are two categories of DTC's that apply to OBD II. They are listed
below with Type A being the more severe.
Type A
1. Emissions related.
2. Requests illumination of the MIL after one failed driving cycle.
3. Stores a freeze frame DTC after one failed driving cycle.
Type B
1. Emissions related.
2. Sets a Pending Trouble Code after one failed driving cycle.
3. Clears a Pending Trouble Code after one successful driving cycle.
4. Turns on the MIL after two consecutive failed driving cycles.
5. Stores a freeze frame after two consecutive failed driving cycles.

There are a lot more, including the 'P1xxx' codes that are manufacturer specific, but that'll do for a start...

Here's some more - instrument cluster specific, but generic across all sorts of vehicles as a quick Google search will show. I've also got the equivalent SAE codes listed, which are the official generic ones, the ones that are displayed on the dash are an FMC code format as far as I can tell.

This lot suggests the 262 DTC code is an SCP error - nothing to worry about, just a comms glitch. And any other DTC code that appears on the dash is going to correspond to the second column of the data below, any other codes aren't displayed on the dash, you'll need a readout device to get them.

The table formatting is all messed up, but you should get the idea, the titles should be in 3 columns.

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